Now, to the dramatic final moments in the massive nationwide manhunt for a suspected cop killer. The man gunned down after robbing a bank in phoenix. The final standoff witnessed by a 911 caller. Linsey davis has the story. I just saw somebody run into the compass bank on thomas and 20 -- 34th AVENUE, WITH A MASK On. Reporter: He didn't know it yet. But this caller was about to witness the moment a massive manhunt for a suspected cop killer came to aeadly end. He's wearing a bandanna around his mouth. Covering his eyes and face. Reporter: This newly released surveillance video shows mario edward garnet attempting to rob a bank in phoenix on saturday. The 40-year-old already wanted for attempted armed robbery of a bank in georgia and another one in tupelo, mississippi, where he allegedly shot and killed a police officer, and wounded another. He entered the bank. He put a lock of some type on the door. He pulled out a weapon and said this was a robbery. Reporter: The attempted heist in phoenix would be his last. He's running out. He's running out. They're shooting. They're shooting. Holy crap. Reporter: After demanding cash from the bank's tellers, garnet walked out the front door, allegedly firing at awaiting officers. That's when police shot him dead. The guy pulled a gun. Started shooting at the officers. One guy down. He's down. That's crazy. Reporter: For "good morning america," linsey davis, abc news, new york.

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